1. Qualitative impairment in social interaction, as manifested by at least two of the following:
   
   • marked impairment in the use of multiple nonverbal behaviours such as eye-to-eye gaze, facial expression, body postures, and gestures to regulate social interaction
   • failure to develop peer relationships appropriate to developmental level
   • a lack of spontaneous seeking to share enjoyment, interests, or achievements with other people (e.g., by a lack of showing, bringing, or pointing out objects of interest to other people)
   • lack of social or emotional reciprocity
2. Restricted repetitive and stereotyped patterns of behaviour, interests, and activities, as manifested by at least one of the following:
   
   • encompassing preoccupation with one or more stereotyped and restricted patterns of interest that is abnormal either in intensity or focus
   • apparently inflexible adherence to specific, non-functional routines or rituals
   • stereotyped and repetitive motor mannerisms (e.g., hand or finger flapping or twisting, or complex whole-body movements)
   • persistent preoccupation with parts of objects
3. The disturbance causes clinically significant impairment in social, occupational, or other important areas of functioning
4. There is no clinically significant general delay in language (e.g., single words used by age 2 years, communicative phrases used by age 3 years)
5. There is no clinically significant delay in cognitive development or in the development of age-appropriate self-help skills, adaptive behaviour (other than in social interaction) and curiosity about the environment in childhood
6. Criteria are not met for another specific Pervasive Developmental Disorder or Schizophrenia

Pervasive Developmental Disorder – Not Otherwise Specified

This category should be used when there is a severe and pervasive impairment in the development of reciprocal social interaction or verbal and nonverbal communication skills, or when stereotyped behaviour, interests, and activities are present, but the criteria are not met for a specific PDD, Schizophrenia, Schizotypal Personality Disorder, or Avoidant Personality Disorder. For example, this category includes "atypical autism" - presentations that do not meet the criteria fro Autistic Disorder because of late age at onset, atypical symptomatology, or subthreshold symptomatology, or all of these.